Electric post-hole digger



ELECTRIC POST-HOLE DIGGER Filed Feb. 27, 1967 INVENTORS. Harry E, ear/sf Jose /2 u.

United States Patent ()flice 3,429,386 Patented Feb. 25, 1969 Filed Feb. 27, 1967, Ser. No. 618,944 U.S. Cl. 175- 170 Claims Int. Cl. E21c 1/02, 1/14 ABSTRACT OF THE DISCLOSURE This invention relates to powered tools and more particularly to a portable hand-held electric post hole digger, which employs large and small gears, and an electric motor.

It is the main purpose of this invention to provide an electric post hole digger which will operate in the manner of an automobile starter, when starting an automobile engine, the larger gear being turned by an electrically operated smaller gear.

Another object of this invention is to provide an electric post hole digger which will have an electric motor mounted by flange means to the face plate of the apparatus and in which the device is operated by closing the starter switch which is mounted on a handle of the apparatus, the starter switch being arranged to activate a solenoid which then serves to energize the driving motor which will contain an inertia spring arrangement for engaging the small diameter gear to the large diameter gear which will drive the auger.

Another object of this invention is to provide an electric post hole digger which will have the inertia spring arrangement which, together with the starting switch and the electrical circuit, serves as a clutch providing protection for the apparatus in the event the anger is stopped.

Still another object of this invention is to provide an electric post hole digger which will have an extending handle secured to the base plate of the apparatus which will be used to counter-balance the weight of the drive motor and the rotation of the auger.

Other objects and advantages of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawing wherein a satisfactory embodiment of the invention is shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawing:

FIGURE 1 is a cross-sectional view taken along the lines 11 of FIGURE 2;

FIGURE 2 is a top plan view of the post hole digger of this invention shown with the top of the housing partly broken away.

According to this invention, an electric post hole digger is provided with a circular base plate 11 made of metal or other suitable material. A hollow cylindrical housing 12 having an angular flange 13 is secured to an extension 14 of base plate 11 by means of a plurality of threaded bolts 15. A plurality of similar bolt fasteners 15' in conjunction with bolt fasteners 15 secure the flange 13 to a handle extension 16 and the extension 14. Handle extension 16 is provided with a hand-grip 17 having an opening 18 for receiving the fingers of the operator. A pair of threaded bolt fasteners 19 provides further means of securing handle extension 16 to electric post hole digger 10 at the base plate 11. A large diameter gear 20 is secured to a vertical shaft 21 which is freely and rotatably recieved Within a bearing 22 at its lower extremity and is freely received within a bearing 23 at its upper extremity. Bearing 23 being secured to the housing 12. Shaft 21 at its lower extremity is freely received within opening 24 of baseplate 11 and a pair of bolt fasteners 25 secure bearing 22 to baseplate 11, thus preventing its rotation during the operation of digger 10. The lower extremity of shaft 21 is adapted to receive the shank 26 of auger 27. A small diameter gear 28 adapted to engage gear 20 within housing 12 is secured to a motor shaft 29 of motor 30 and the inertia spring device 31 which is well known in the art provides for automatically raising gear 28 to thus engage gear 20 in order to rotate auger 27 while it simultaneously serves as described below, as a clutch in the event that auger 27 is stopped during the drilling operation. Electric motor 30 is secured to baseplate 11 by means of a plurality of threaded bolt fasteners 32 thus external of post hole digger 10. An offset handle 33 is provided with a starting switch 34 which when closed will rotate motor 30 thus engaging gear 28 with gear 20 which will then rotate auger 27 The inertia spring device referred to is of the type commonly used with automobile starter motors and is generally described in Patents Nos. 1,550,775, 1,551,787, and 1,561,683. Such a device has a rod or preferably a solenoid for moving the small gear 28 into engagement with the large gear 20. The motor shaft 29 is provided with a spiral keyway and the gear 28 is provided with a co-operating key. Rotation of the motor maintains the gears in driving engagement. If the auger were stopped, for example by a stone, the operator would release the starting switch 34 which would allow the gears to reverse slightly and cause disengagement of the small gear 28 from the large gear 20.

It will be noted that the inertia spring 31 gears 20 and 28 and also bearings 22 and 23 are completely enclosed within housing 12 thus preventing possible injury to the operators and also protecting said components from damage.

What we now claim is:

1. A post hole digger for drilling holes in the earth comprising:

(a) a base;

(b) a driven shaft rotatably mounted to the base;

(0) an auger fixed to the shaft for rotation therewith for drilling holes when rotated;

(d) a motor fixed to the base, spaced from the shaft, and drivingly connected to the shaft for applying a torque to the auger when the motor is actuated;

(e) means for actuating the motor; and

(f a handle, secured to the base and extending therefrom, positioned on substantially the side of the shaft opposite from the motor;

wherein an operator may grip the handle and thereby stabilize the post hole digger and counterbalance the weight of the motor.

2. A post hole digger according to claim 1, wherein the handle extends radially outward from said shaft.

3. A post hole digger according to claim 2, wherein the handle extends radially outward on a line intersecting the axis of the motor.

3 4 4. A post hole digger according to claim 1, wherein disen agement of said gear by said spring means is provided for disengaging the motor from the bias.

shaft when the motor is not actuated. 5. A post hole digger according to claim 4, f enc s Cited wherein the disengaging means comprises 5 UNITED STATES PATENTS (a) a portion of the shaft of the motor having a Spiral keyway thereby 1,982,646 12/1934 Dick 175170 (b) a gear on said shaft keyed to said keyway f r g fi drivingly engaging the auger when the m tor ewe 10 5 35%: @5122; 52133 exme (c) a spring biased solenold hnked t0 s ld ge r 3,282,339 11/1966 Hasha 175*170 for moving said gear into said driving engagement with the auger when actuatedand A. LEP K P E (d) a starter switch for manually actuating said JAMES PIN rlma'y xamme' solenoid and said motor; 15 US CL wherein release of the starter switch causes 173 117 

